Just bought a 1968 (originally was 427/435..currently has a CE replacement block from 69)) and I believe it has a M22 vice M21. Intent at some point in the near future is to crawl under and check numbers/code. I know it has the factory 411 rear end (Code FB) so that is the first reason I'm thinking it could be a M22- realize that's not a guarantee. The other reason is that I had a M21 in my 71 coupe and in order to get it in reverse you had to pick up on the shifter T sleeve to get it into reverse. My 68 does not have this and I've notice that the distance b/w gears (1st to 2nd, 3rd to 4th, etc) is shorter and stiffer- less slop. Am I on to something, or am I just going to have to wait until I can get under her and grab the numbers. Thanks in advance!

V/r
Joe

 

The shifter has no bearing on weather it is a M21 or M22. Does the transmission whine when driving vs your M21. The straighter cut gears are noisier than the M21 gears. The numbers should tell the real stroy.

 

Joe

You'll need to get under there and get the numbers. Here's the guide:

http://www.5speeds.com/muncie2.htm

 

All Corvette 4 speed transmissions used between 68-76, used the same shifter. The only thing unique about the 68 shifter, was that it used a chrome ball, instead of the black chrome ball, found on 69 up shifters. If you don't have the "T" handle lock out, them someone has changed the shifter.

If you have a real 68 M-22, I don't think you can identify it without looking inside it. All 68 Muncies used the 660 case. A 68 M-22 will have a 10 tooth input spline with no rings in it and a 26 tooth output spline. You can't always go by the ring (or lack there of) on the input shaft, to identify an M-22, as replacement input shafts don't usually have any rings.

If it is the original trans to your car, it will have a date code and your car's VIN, stamped on the machined vertical surface, by where the tail housing attaches to the main case. The date code consists of a P for the Muncie plant, an "8" for the 68 model year, a letter for the month, and a 2 digit date for the day. P8A22 would be a 68 Muncie 4 speed, assembled on January 22, 1968. This would be followed by your VIN derivative, something along the line of 18S1XXXXX.

69-74 Muncies had a letter code after the date, to indicate which Muncie the trans was. "A" = M-20, "B" = M-21 and "C" = M-22; unfortunately 66-68 Muncies don't carry this identifier.

 

Looks like I have some homework to do, great info, thanks everyone, appreciate the assistance.

Joe

 

I had a Hurst shifter on my '71 before the TKO swap, and I used to lift the "T" to get reverse up until the day I removed it...THEN I found out it isn't a lockout shifter!!!!!

 

Yep, I have 2 Hurst shifters and 2 stock shifters. The Hurst don't have the neutral safety switch or the reverse lock-out.

 

M22 use for model year 1968 was only with the L-88s. Just the same, you could buy them over the counter at Chevrolet.

Stock 4 speed shifters had the T-handle reverse lock out.

 

No shifter, OEM or Hurst has a neutral safety switch.

 

You can tell if it is a M22 the minute you start moveing down the road. It will wine in first, second and third, most noticable in first .
If you go to u-tube you should be able to find some video's and hear what they sound like .
When I first got my 71 I thought there was something wrong with the transmition but it is normal wineing.

Bill

 

it could also be something wrong with the transmission.. so many people think they have a M22 because it whines, when it is really a M20 and only whines because it needs rebuilt or is out of oil.

As stated above, only L88's got M22 in 68 so you do not have a factory M22.

also, you never knows what you really have until you pull the side cover and look. the numbers may say m22 or not, but with 43 year old transmission and car, one never knows what is really inside. who knows what was done 25 years and 6 owners ago.

 

 

Amazing. I was doing an internet search on another topic and this discussion from 2011 popped up. I'm surprised that nobody got this right. Since the owner is thinking it is an M22 because of the 4:11 rear, that means he thinks an M22 could be original to the car. Only problem is, in '68 and '69 the only Corvettes that got M22's were L88's. NO 435 cars in either year had a factory installed M22. ALSO, although later (around '70 or '71 if I recall) all of the M20's and M21's got the big output shaft and lower drain plug, so that's no longer a sign, in 68 the M20 & M21 did not have the low drain plug in the case. After all this time this may not interest anybody, but it could be that somebody else stumbles on this in a google search also.

 

...I miss the old "pre-Internet" days of young 20 something's every Camaro, Nova or Chevelle that was for sale or talked about at a local cruise in or car show had an M-22 Rock Crusher trans. Ah, the good ol' days!!!

 

And every hot rod, 60's Impala and clapped out old pick up advertised for sale, were claiming they had a Corvette engine in them. Actually, you still see ads from time to time, advertising cars with a Corvette engine and/or an M-22.

 

LOL, I've had several people tell me, when I've mentioned getting a 5-speed box, that they would disown me for ditching that glorious gear whine. Tell you the truth, it's clearly part of the charm. And, before anyone gets excited, and starts jumping up and down, no, it's not orginal to the car...